Using Ultrafast X-ray Spectroscopy To Address Questions in Ligand-Field Theory: The Excited State Spin and Structure of [Fe(dcpp)2]2

Research output: Contribution to journalJournal article – Annual report year: 2019Researchpeer-review

  • Author: Britz, Alexander

    European XFEL, Germany

  • Author: Gawelda, Wojciech

    European XFEL, Germany

  • Author: Assefa, Tadesse A.

    European XFEL, Germany

  • Author: Jamula, Lindsey L.

    Michigan State University, United States

  • Author: Yarranton, Jonathan T.

    Michigan State University, United States

  • Author: Galler, Andreas

    European XFEL, Germany

  • Author: Khakhulin, Dmitry

    European XFEL, Germany

  • Author: Diez, Michael

    European XFEL, Germany

  • Author: Harder, Manuel

    Deutsches Elektronen-Synchrotron, Germany

  • Author: Doumy, Gilles

    Argonne National Laboratory, United States

  • Author: March, Anne Marie

    Argonne National Laboratory, United States

  • Author: Bajnoczi, Eva

    Hungarian Academy of Sciences, Hungary

  • Author: Nemeth, Zoltan

    Hungarian Academy of Sciences, Hungary

  • Author: Pápai, Mátyás Imre

    Department of Chemistry, Technical University of Denmark, Kemitorvet, 2800, Kgs. Lyngby, Denmark

  • Author: Rozsalyi, Emese

    Hungarian Academy of Sciences, Hungary

  • Author: Sárosiné Szemes, Dorottya

    Hungarian Academy of Sciences, Hungary

  • Author: Cho, Hana

    Korea Research Institute of Standards and Science, Korea, Democratic People's Republic of

  • Author: Mukherjee, Sriparna

    North Carolina State University, United States

  • Author: Liu, Chang

    North Carolina State University, United States

  • Author: Kim, Tae Kyu

    Pusan National University, Korea, Democratic People's Republic of

  • Author: Schoenlein, Robert W.

    Lawrence Berkeley National Laboratory, United States

  • Author: Southworth, Stephen H.

    Argonne National Laboratory, United States

  • Author: Young, Linda

    Argonne National Laboratory, United States

  • Author: Jakubikova, Elena

    North Carolina State University, United States

  • Author: Huse, Nils

    University of Hamburg, Germany

  • Author: Vankó, György

    Hungarian Academy of Sciences, Hungary

  • Author: Bressler, Christian

    European XFEL, Germany

  • Author: McCusker, James K.

    Michigan State University, United States

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We have employed a range of ultrafast X-ray spectroscopies in an effort to characterize the lowest energy excited state of [Fe(dcpp)2]2+ (where dcpp is 2,6-(dicarboxypyridyl)pyridine). This compound exhibits an unusually short excited-state lifetime for a low-spin Fe(II) polypyridyl complex of 270 ps in a room-temperature fluid solution, raising questions as to whether the ligand-field strength of dcpp had pushed this system beyond the 5T2/3T1 crossing point and stabilizing the latter as the lowest energy excited state. Kα and Kβ X-ray emission spectroscopies have been used to unambiguously determine the quintet spin multiplicity of the long-lived excited state, thereby establishing the 5T2 state as the lowest energy excited state of this compound. Geometric changes associated with the photoinduced ligand-field state conversion have also been monitored with extended X-ray absorption fine structure. The data show the typical average Fe-ligand bond length elongation of ∼0.18 Å for a 5T2 state and suggest a high anisotropy of the primary coordination sphere around the metal center in the excited 5Tstate, in stark contrast to the nearly perfect octahedral symmetry that characterizes the low-spin 1A1 ground state structure. This study illustrates how the application of time-resolved X-ray techniques can provide insights into the electronic structures of molecules-in particular, transition metal complexes-that are difficult if not impossible to obtain by other means.
Original languageEnglish
JournalInorganic Chemistry
Volume58
Issue number14
Pages (from-to)9341-9350
Number of pages10
ISSN0020-1669
DOIs
Publication statusPublished - 2019
CitationsWeb of Science® Times Cited: No match on DOI

ID: 189123453